Neptune’s Small Moons

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Neptune’s innermost four moons are

  • Naiad,
  • Thalassa,
  • Despina and
  • Galatea.

Neptune also has several tiny distant and unnamed moons which were discovered recently.

Naiad

Neptune III

Naiad ( “NAY ed” ) is the innermost of Neptune’s known satellites:

        orbit:    48,200 km from Neptune
        diameter: 58 km
        mass:     ?

The Naiads were the nymphs who lived in and presided over brooks, springs, and fountains.

The last of the satellites discovered in 1989 by Voyager 2.

Naiad, Thalassa, Despina and Galatea are all irregularly shaped.

More about Naiad

Thalassa

Neptune IV

Thalassa (“tuh LASS eh”) is the second of Neptune’s known satellites:

        orbit:    50,000 km from Neptune
        diameter: 80 km
        mass:     ?

Thalassa was a daughter of Aether and Hemera. “Thalassa” is also the Greek word for “sea”.

Discovered in 1989 by Voyager 2.

More about Thalassa

Despina

Neptune V

Despina is the third of Neptune’s known satellites:

        orbit:    52,600 km from Neptune
        diameter: 148 km
        mass:     ?

Despina was a nymph, the daughter of Poseidon (Neptune) and Demeter.

Discovered in 1989 by Voyager 2.

More about Despina

Galatea

Neptune VI

Galatea (“gal eh TEE eh”) is the fourth of Neptune’s known satellites:

        orbit:    62,000 km from Neptune
        diameter: 158 km
        mass:     ?

Galatea was a Sicilian Nereid loved by the Cyclops Polyphemus. (Not related to the maiden who was originally a statue carved by Pygmalion and who was brought to life by Aphrodite.)

Discovered in 1989 by Voyager 2.

More about Galatea

Open Issues

  • We know next to nothing about these moons. Even the basic orbital and size data are not very accurate.